Improvement in pivot-bridges



T. C. CLARKE, A; BONZANO & J. GRIFFEN. Uhprovement in Pivot-Bridges.

Patented June 18, 1872,

UNITED STATES PA'r'rnv'r OFFIoE.

THOMAS C. CLARKE, OF PHILADELPHIA, AND ADOLPHUS BONZANO AND JOHNGRIFFEN, OF PH(ENIXVILLE, ASSIGNOBS TO CLARKE, REEVES & 00., OFPHILADELPHIA, PENNSYLVANIA.

IMPROVEMENT IN PIVOT-BRIDGES.

Specification forming part of Letters Patent No. 128,115, dated June 18,1872.

Specification describing certain Improvements in Pivot-Bridges, inventedby THOMAS C. CLARKE, of Philadelphia, and ADOLPHUS BONZANO and JOHNGRIFFEN, of Phoenixville, Pennsylvania.

Improvements in Pivot-Bridges.

Our invention relates to certain improvements in pivot-bridges, toofully explained hereafter to need preliminary description; the saidimprovements having for their object, first, the ready withdrawal of thecorner-supports of the bridge when the latter has to be turned on itspivot, and the ready restoration of these supports when the position ofthe bridge demands them; and second, the selfcentering of the bridge, sothat the nice and tedious manipulative adjustment demanded in order thatthe rails of the bridge may coincide with those of the permanent track,is rendered unnecessary.

' In the accompanying drawing, Figure 1 is a view of a portion of theend of a pivot-bridge; Fig. 2, a side view of a portion of one end ofthe bridge; Fig. 3, a plan view of Fig. 1; and Fig. 4, a perspectiveview illustrating a part of our invention.

- A and A are two transverse beams at one end of the bridge, these,together with other transverse beams of like character, supporting thelongitudinal beams B, across which extend the ties D for receiving therails ad. The transverse beams A are secured to the lower chord-beams bysuspension-bolts 0, this lower chord forming part of a truss-frame ofwhich the pivot-bridge is composed, and of which F represents a portionof one of the diagonal end posts. To the transverse beam A are hung, bymeans of a pin, f, a series of links, 13 i, and to the latter are hung,by means of a'pin, j, a series of similar links, m, and to a pin passingthrough the lower ends of the latter series of links are hung tworollers, 19 p, which are guided vertically by brackets q q secured tothe under side of the beams A. The two sets of links, as will be seenhereafter, form a knee-joint, to the central pin j of which two rods, GG, are jointed, the opposite ends of these rods being connected to thelower ends of arms H, which are hung to the transverse beams A A, andthese arms are connected, by a rod, I, to lugs on a nut, J, which isadapted to vertical guides arranged between the two beams A A, the saidnut being-also connected by similar appliances to knee-joint linksarranged at the opposite corner of the bridge, which is not shown in thedrawing. The nut J is controlled by a vertical screw so confined tosuitable bearings h, secured to the beams A A, that while it can beturned easily it is incapable of vertical movement. This screw may beoperated by any suitable mechanism but we prefer to operate it from acentral point on the pivot-bridge and to connect the operating mechanismby means of a horizontal shaft extending along the bridge beneath theties, one end of the shaft being geared by bevel-wheels to the screw Kat one end of the bridge, and the opposite end to a similar screw at theopposite end of the bridge, so that the knee-joint links at all fourcorners of the bridge may be operated simultaneously from one point. Theouter ends of the rails a, a at each end of the bridge admit of beingraised and lowered ,by the same mechanism which operates the knee-joints. Thus the rails a a in Fig. l are connected by rods y y to therods I I, and these rails are adapted to chairs d d, which are securedto the permanent roadway or permanent part of a bridge, and whichreceive the ends of the permanent rails b b of the track, the chair thusinsuring the coincidence of the rails of the pivot-bridge with those ofthe permanent track.

As seen in the drawing, the bridge is supposed to be closed and free forthe passage of trains, the rollers 19 at the lower end of theknee-jointed links at each corner of the bridge bearing in a cavity inthe top of a plate, t, secured to the foundation or pier; and, the pinsof the knee-joint links being in the same ver tical line, the linksafford a steady support for the bridge at each of its four corners. Whenit is necessary to swing the bridge round the screw K at each end of thebridge is turned so as to elevate the nuts J. This consequently drawsthe rods G and I in the direction of the arrows, and therefore so actson the knee-joint links as to elevate the rollers 19 p in their guides;and this is continued until the bridge 2 maria is in the first instancelowered and supported on its center pivot only, and afterward until therollers are clear of their bearings. Simultaneously with this movementof the kneejoint links the outer ends of the rails. owing to theirconnections with the rods I I, were elevated clear of the chairs (1 d,as seen in Fig.

4, and consequently the bridge is free to be turned on its pivot. Inrestoring the bridge to its original position it is turned round untilthe rollers p p of the knee-j oint links are-above the cavity of thefoundation-plate t. It is very rarely, however, that the bridge .can bearrested in its movement at a point where the said rollers are directlyabove the center of the said cavity; but as soon as the screws K areoperated to straighten the knee-joint links and the rollers q begin tobear upon the plates 25 the weight on the rollers will induce them todescend into the cavities of the plates; and hence as the straighteningof the kneejoints is continued the bridge will be slightly turned untilthe rollers have arrived at the most depressed portion of the cavitiesin the plates, and there remain while the straightening of theknee-jointed links is continued until their pins are in the samevertical line, as shown in Fig. 1. After the bridge had adjusted itselfin the manner described during the preliminary straightening of thelinks, and this straightening was continued, the rails a a on the bridgedescended until they rested in and were confined laterally by the shoesd d of the permanent track. It will be seen, therefore, that byconnecting these rails a a to the mechanism which operates theknee-joints the said rails are elevated out of the chair simultaneouslywith the releasing of the bridge from its corner-bearings, and when theknee-joints become the corner-bearings the rails are lowered into thechairs, and their coincidence with the rails of the permanent track isthereby insured. The accidents which have frequently occurred throughthe non-coinciding of the rails of a pivot-bridge with those of thepermanent track are thus prevented.

The knee-joint bearings at the corner of the bridge possess thisimportant advantage, that they can be operated with comparatively littleexertion, either through the medium of the mechanism described or anyequivalent operating devices.

Although we have shown and described a pivot-bridge constructed in amanner which we deem most appropriate, it should be un derstood that ourimprovements are applicable to any,pivot-bridge. A chan ge in theoperating mechanism may he demanded in a bridge constructed in a mannerdifiering from that described, but the principal features may remain;these features being the knee-joint links, forming corner-supports,which can be easily withdrawn, and the plates t, which render the bridgeself-centering.

. We claim as our invention- 1. The combination, with a pivot-bridgesubstantially as described, of knee-joint supports and the mechanismdescribed, or any equivalent to the same, for operating the said joints.

2. In combination with a pivot-bridge havin g movable links as supports,we claim plates t, constructed, substantially as described, so as torender the bridge self-centering.

In testimony whereof we have signed our names to this specification inthe presence of two subscribing witnesses.

THOMAS C. CLARKE. ADOLPHUS BONZANO. JOHN GRIFFEN.

Witnesses to the signature of THOMAS C. CLARKE:

WM. A. STEEL, HARRY SMITH. Witnesses to the signatures of ADOLPHUSBONZANO and JOHN GRIFFEN:

P. G. CAREY, M. Gn'LIPPERT.

